Kevin starts counting at 42, and he counts by threes. If 42 is the 1st number that Kevin counts. what is the 8th number that he counts?
What is the first number that he counts? $42$ What is the second number that he counts? $\begin{align*}&42 + 3 \\ &= 45\end{align*}$ What is the third number that he counts? $\begin{align*}&42 + 3 + 3 \\ &= 42 + (2 \times 3) \\ &= 48\end{align*}$ What is the 8th number that he counts? $\begin{align*}&42 + (7\times3) \\ &= 42 + 21 \\ &= 63\end{align*}$